Questions tagged [integer]
For challenges involving the manipulation of integers.
278
questions
22
votes
27answers
971 views
Output with the same length always
With challenges like Output with the same length as the code and Create output twice the length of the code, I thought of a separate, but similar challenge.
The task is to produce an output. It can ...
9
votes
0answers
111 views
Decompose Commutators
A theorem in this paper1 states that every integral n-by-n matrix M over the integers with trace M = 0 is a commutator, that means there are two integral matrices A,B of the same size ...
32
votes
35answers
5k views
Repeated! Factorials!
Not to be confused with Find the factorial!
Introduction
The factorial of an integer n can be calculated by
$$n!=n\times(n-1)\times(n-2)\times(...)\times2\times1$$...
27
votes
28answers
4k views
Inverse Colombian Function
Let's define a sequence: The n digit summing sequence (n-DSS) is a sequence that starts with n. If the last number was k, then the next number is k + digit-sum(k). Here are the first few n-DSS:
...
5
votes
4answers
413 views
Find X,Y,Z coordinates from index
Introduction
I began studying the Collatz Conjecture
And noticed these patterns;
0,1,2,2,3,3...A055086, and 0,1,2,0,3,1...A082375,
in the numbers that go to 1 in one odd step,
5,10,20,21,40,42......
23
votes
24answers
3k views
Robbers: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the robber's thread. The cop's thread is here.
The cops will pick any sequence from the OEIS, and write a program p that prints the first integer from ...
37
votes
27answers
4k views
Cops: The Hidden OEIS Substring
This is a Cops and Robbers challenge. This is the cop's thread. The robber's thread is here.
As a cop, you must pick any sequence from the OEIS, and write a program p that prints the first integer ...
25
votes
56answers
6k views
Integer Lists of Noah
Introduction:
I think we've all heard of it, but here a very brief summary: Noah gathered two of every species of animal on the planet, male and female, to save in his Ark during a great flood. The ...
2
votes
3answers
114 views
Sum of multiples of powers of ten of an integer [duplicate]
Write a function to produce, for a non-negative integer, a string containing a sum of terms according to the following:
...
-6
votes
5answers
174 views
Is this number a palindrome? [closed]
Input
A single integer in your language's preferred format. This format is non-negotiable (no input as strings, arrays of digits, etc.), but standard I/O formats do apply if otherwise it would be ...
37
votes
31answers
14k views
Do the 26 richest billionaires own as much wealth as the poorest 3.8 billion people?
Introduction:
A few days ago I read this post with the same title when I came across it in the HNQ. In this question it is being discussed if the claim of president-candidate Bernie Sanders, who ...
43
votes
12answers
3k views
Prime parity peregrination
The purpose of this challenge is to graphically depict a walk on the plane, where the direction of each step \$k\$ is determined by the primality of \$k\$ and the parity of its binary expansion. ...
5
votes
0answers
164 views
Fastest way to iterate over sublattice of discrete lattice
I need to construct a functor that iterates over the linear representation of a sub-lattice of size \$d_x,d_y,d_z,d_q\$ embedded in a lattice of size \$n_x,n_y,n_z,n_q\$. The sub-lattice corner is ...
21
votes
6answers
974 views
Subtract the Folded Matrix
Challenge:
Given an NxN matrix where \$N\geq2\$ and one of eight distinct 'folding options', output a 2D array/list with the subtracted values.
The eight folding options are: left-to-right; right-to-...
11
votes
6answers
854 views
Group Integers by Originality
Introduction:
I collect twisty puzzles. Most twisty puzzles are produced and sold by Chinese companies. Most well-known companies ask permission from puzzle designers to produce their designs and ...
20
votes
22answers
2k views
Rotated Position of Integers
Challenge:
Input:
A sorted list of positive integers.
Output:
The amount of integers which are still at the exact same index, after rotating the digits in each integer its index amount of times ...
8
votes
4answers
609 views
Leading and Suffering Numbers
Introduction:
In Dutch, the words leading and suffering, being 'leiden' and 'lijden' respectively, are pronounced the same way. One is written with a "short ei", and one with a "long ij", as we ...
20
votes
9answers
1k views
Warped chessboard
This challenge is about building a chessboard in which the square size, instead of being constant across the board, follows a certain non-decreasing sequence, as described below.
The board is defined ...
32
votes
21answers
2k views
A Note on N!
J. E. Maxfield proved following theorem (see DOI: 10.2307/2688966):
If \$A\$ is any positive integer having \$m\$ digits, there exists a positive integer \$N\$ such that the first \$m\$ digits of \$...
-2
votes
6answers
244 views
Map values to any multidimensional array [closed]
Codegolf challenge - mapping values in a multidimensional array
[
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]
]
This 2D array is sick of being so false, and wants to ...
23
votes
20answers
1k views
Maximum summed subsequences with non-adjacent items
Introduction:
Inspired by these two SO questions (no doubt from the same class): print the elements in the subarray of maximum sum without adjacent elements java and Maximum sum of non adjacent ...
11
votes
6answers
1k views
Area of a 2D convex hull
You are given an array/list/vector of pairs of integers representing cartesian coordinates \$(x, y)\$ of points on a 2D Euclidean plane; all coordinates are between \$−10^4\$ and \$10^4\$, duplicates ...
27
votes
13answers
3k views
Valid Badminton Score?
Introduction:
I saw there was only one other badminton related challenge right now. Since I play badminton myself (for the past 13 years now), I figured I'd add some badminton-related challenges. ...
26
votes
22answers
2k views
The Digit Triangles
Challenge:
Input: A positive integer \$n\$
Output:
Create a list in the range \$[1,n]\$, and join it together to a string (i.e. \$n=13\$ would be the string ...
30
votes
23answers
8k views
Could you please stop shuffling the deck and play already?
Challenge:
Input: A list of distinct positive integers within the range \$[1, \text{list-size}]\$.
Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
14
votes
11answers
876 views
Source permutation
A permutation of a set \$S = \{s_1, s_2, \dotsc, s_n\}\$ is a bijective function \$\pi: S \to S\$. For example, if \$S = \{1,2,3,4\}\$ then the function \$\pi: x \mapsto 1 + (x + 1 \mod 4)\$ is a ...
11
votes
31answers
758 views
Sum integers in a string
Input
A string.
Output
The sum of all integers in the line.
Constraints
1≤Length of line≤500
Sample test Case
Input
the 5is 108 seCONd4 a
Output
...
33
votes
5answers
8k views
Historical difference between `/` and `÷` in mathematical expressions
Introduction:
Inspired by a discussion that is already going on for many years
regarding the expression \$6÷2(1+2)\$.
With the expression \$6÷2(1+2)\$, mathematicians will quickly see that ...
7
votes
7answers
536 views
Check type of an integer
You will receive an integer less than 2000000000 and bigger than -2000000000 and you have to test what type(s) of number this is out of:
...
4
votes
9answers
285 views
Floating over the integers
As you may know, the typical binary floating point numbers in a computer language are quite different than the typical integer numbers in a computer language. Floating point numbers can represent a ...
20
votes
17answers
2k views
Square Root Distance from Integers
Given a decimal number k, find the smallest integer n such that the square root of n is ...
19
votes
25answers
2k views
23
votes
3answers
2k views
The Path Of The Wildebeest
Golf a program or function which gives the \$n^{\text{th}}\$ location of the wildebeest who starts at square \$1\$ on an infinite chessboard which is numbered in an anti-clockwise square spiral, where ...
24
votes
15answers
3k views
Matrix Jigsaw Puzzles
Input:
An integer n
Two equal-sized square matrices (with their width/height being a multiple of n)
Output:
One of two ...
24
votes
38answers
2k views
Enumerate each series of identical numbers in-place
Given a list of strictly positive integers, go through each distinct number and replace all occurrences of it with successive indices (zero or one based) of a new series.
Examples
...
23
votes
18answers
2k views
Collapsing numbers
Let's define the a function on natural numbers \$n\$, written as base 10 digits \$d_k\; d_{k-1}\; \dotsc\; d_1\; d_0\$, as follows:
As long as there are equal adjacent digits \$d_i\;d_{i-1}\$, ...
22
votes
13answers
3k views
Eight coins for the fair king
This is a "counterpart" of another puzzle, Eight coins for the fair king on Puzzling.SE.
You can read the above puzzle for the background. The details about this puzzle are as follows.
A set of 8 ...
21
votes
26answers
2k views
Digital Sumorial
Given an input n, write a program or function that outputs/returns the sum of the digital sums of n for all the bases 1 to ...
25
votes
6answers
1k views
Prime containment numbers (speed edition)
This is sequence A054261
The \$n\$th prime containment number is the lowest number which contains the first \$n\$ prime numbers as substrings. For example, the number \$235\$ is the lowest number ...
21
votes
14answers
2k views
Prime containment numbers (golf edition)
This is sequence A054261.
The \$n\$th prime containment number is the lowest number which contains the first \$n\$ prime numbers as substrings. For example, the number \$235\$ is the lowest number ...
23
votes
25answers
2k views
Sort by Largest Digit(s)
Challenge:
Given a list of integer, sort descending by their single largest digit(s). The order for numbers with the same largest digit are then sorted by second largest digit, etc.
We ignore ...
17
votes
10answers
2k views
Reciprocal copycats
Let \$A\$ be a positive integer consisting of \$n\$ decimal digits \$d_1,d_2,...,d_n\$. Let \$B\$ be another positive integer.
For the purpose of this challenge, we call \$A\$ a copycat of \$B\$ if ...
24
votes
15answers
2k views
All the single eights
Given a non-empty rectangular array of integers from 0 to 9, output the amount of cells that are ...
10
votes
9answers
1k views
Through Space and Time
Introduction:
In general we usually speak of four dimensions: three space dimensions for x, y, and ...
15
votes
45answers
2k views
Print the Lost numbers
As a big fan of the Lost TV series, I always got intrigued by the sequence of numbers that repetitively appears on the episodes. These numbers are:
\$ 4, 8, 15, 16, 23, 42\$ (A104101)
Using any ...
14
votes
27answers
2k views
The inverse Collatz Conjecture
I think the Collatz Conjecture is already well-known. But what if we invert the rules?
Start with an integer n >= 1.
Repeat the following steps:
If n is even, multiply it by 3 and add 1.
If n is ...
24
votes
25answers
1k views
New Neighbour Sequence
The non-negative integers are bored of always having the same two* neighbours, so they decide to mix things up a little. However, they are also lazy and want to stay as close as possible to their ...
17
votes
19answers
2k views
The Written Digits Sequence
Here's a reasonably trivial sequence which is not in the Online Encyclopedia of Integer Sequences.
Start with an empty sequence then define each term as the number of characters required to write out,...
9
votes
24answers
952 views
Multiplicative undelta
Let us define the "multiplicative deltas" of values \$[\; a_0, \cdots a_N, \;]\$ as:
$$
[\; a_1 / a_0, \cdots, a_{i+1} / a_i, \cdots, a_N / a_{N-1} \;]
$$
The reverse operation - namely "...
14
votes
16answers
853 views
Length of a UTF-8 byte sequence
Determine the length of a UTF-8 byte sequence given its first byte. The following table shows which ranges map to each possible length:
...
